Application of Pyrrolidinium-Based Ionic Liquid as Solvent for the Liquid Extraction of Benzene from Its Mixtures with Aliphatic Hydrocarbons

Abstract

The ionic liquids 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMpyr]­[TfO], 1-butyl-1-methylpyrrolidinium bis­(trifluoromethylsulfonyl)­imide, [BMpyr]­[NTf2], and 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr]­[DCA], have been studied as solvents for the extraction of benzene from its mixtures with several aliphatic hydrocarbons. The liquid–liquid equilibrium (LLE) of the ternary systems {octane (1) + benzene (2) + [BMpyr]­[TfO] (3)}, {decane (1) + benzene (2) + [BMpyr]­[TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr]­[TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr]­[NTf2] (3)}, and {dodecane (1) + benzene (2) + [BMpyr]­[DCA] (3)} at T = 298.15 K and atmospheric pressure was carried out. The solute distribution ratio and selectivity values derived from the tie-lines were used to evaluate if the studied ionic liquids can be used as extraction solvents, and the obtained values were compared with those found in the literature for the traditional organic solvents. Finally, experimental LLE data for the ternary mixtures were correlated by means of the non-random two-liquid (NRTL) thermodynamic model.

Comparison of Ionic Liquids to Conventional Organic Solvents for Extraction of Aromatics from Aliphatics

“…Liquid–liquid phase equilibrium, capacity, and selectivity have been reported for several combinations of aliphatics and aromatics using ionic liquids as the extraction solvent. Among the ionic liquids studied, the cations used are mostly imidazolium ,− and pyridinium. ,,,− A few studies use pyrrolidinium, ammonium, ,, morpholinium, and other cations, , while the most investigated ionic liquid anion is bis­(trifluoromethylsulfonyl)­imide ([Tf 2 N] − ). In addition, aromatic extractions have been performed with ionic liquid mixtures in an attempt to improve both selectivity and capacity. − In some cases, infinite dilution activity coefficients of aromatic and aliphatic compounds in ionic liquids have been used as a first pass evaluation of the suitability of a particular ionic liquid for aliphatic–aromatic separation. …”

Reversibility of imido-based ionic liquids: a theoretical and experimental study

“…In the last few decades, ionic liquids (ILs), known as salts in liquid form at (or near) room-temperature, have been receiving signicant interest, with applications as engineering uids [1][2][3][4][5][6] and electrolytes [7][8][9] and for gas absorption [10][11][12][13][14] and biomass dissolution, [15][16][17] mainly because of their appealing properties such as low-melting points and exibilities in structure and function design. [18][19][20] Their properties can be tailored by incorporating anion and cation species and functional groups to serve certain purposes.…”

Understanding liquid–liquid equilibria in binary mixtures of hydrocarbons with a thermally robust perarylphosphonium-based ionic liquid

“…[3][4][5][6][7][8][9][10][11][12][13] Many of these studies have focused on the effects of cation and anion structure on the extraction/ separation of aromatic compounds from hydrocarbon mixtures. [14][15][16][17][18][19][20] Certain ILs when mixed with aromatic compounds such as benzene, toluene, or xylenes in excess concentrations form two distinct liquid phases: an ion-rich phase and an almost pure aromatic phase. [21][22][23][24][25] Furthermore, the ratio of aromatics to ion pairs in the ion-rich phase is surprisingly well-dened, and this behaviour is oentimes referred to as the formation of liquid clathrates.…”